A popular surf spot in Western Australia's south-west remains closed while authorities search for a shark responsible for a fatal attack yesterday.

Kyle James Burden, 21, was killed when he was attacked by the shark just after midday at the popular Boneyards break off Sugarloaf Rock in Bunker Bay, about 300 kilometres south of Perth.

Police say Mr Burden was bitten on the lower half of his body, and died at the scene.

It is understood he was originally from Sydney, and had lived in the Margaret River region for the past two years.

Fellow surfer Hamish McLeay says the death has rocked the community."There was a reaction of shock and amazement, and a little bit of disbelief of course. But the reality is that these things happen," he said.

"I think there's a little bit of realisation going on that there is respect for the ocean and its life.

Navine Eldesouki was at the beach where her children were swimming when the shark attacked.

"It's very sad to think that you're here so close and it just happened when you're sitting on the beach, it is scary to think that," she said.

"The kids were in the water at the time as well, all these people in the water."

Sergeant Craig Anderson says an air and sea search is underway for the shark, believed to be a 4.5 metre great white.

"You know, we'll conduct a thorough search of the area, doing what they can to herd the animal away from the area, definitely no plans for it to be hunted today," he said.

Authorities say they have no intention of killing the shark but the beach is likely to remain closed for several days.

Mr Burden's mother is on her way to WA from Queensland.

It is the first fatal shark attack in Australia since February, when a man diving for abalone was savaged off South Australia, and only the fourth since December 2008.